Fastener driving devices typically have trigger assemblies that operate in either a “sequential” mode (“place and actuate” mode) or a “contact” mode. In sequential actuation trigger assemblies, the nose of the device must be forced against the workpiece before the trigger is enabled. Therefore, the operator cannot simply pull the trigger to fire the device. Rather, the device must be forced downwardly against the workpiece so that a contact trip assembly associated with the nose moves upwardly to engage an actuator that will render the trigger operative, so that the subsequent pulling of the trigger will fire the device. If the tool recoils, no actuation of the device will occur until the trigger is released and the proper sequence of movement is followed.
In contact actuation trigger assemblies, the trigger is pulled before the nose of the device makes contact with the workpiece. This places the actuator in a position such that the device may be actuated every time the nose of the device is forced against the workpiece. With this sequence of activation, the operator can hold the trigger and subsequently force the nose against the workpiece to fire the device.
Each of the sequential and contact actuation trigger assemblies have advantages depending on the specific application. For example, sequential actuation trigger assemblies eliminate the possibility of accidental double actuation of the device. This is particularly advantageous when using the device for placing joist hangers, for example.